1. Technical Field
This invention relates generally to methods and apparatus for controlling the height adjustment of vehicle-mounted devices for use in clearing snow or debris from a road or runway. More particularly, this invention relates to an apparatus and method for utilization of a proximity sensor to control the height adjustment of vehicle-mounted devices for use in clearing snow or debris from a road or runway.
2. History of Related Art
In vehicle-mounted devices for use in clearing snow or debris from a road or runway, the vertical position of the spinning broom assembly determines the amount of contact between the broom bristles and the surface of the road or runway. In prior art systems, the vertical position of the spinning broom assembly is accomplished by the use of a mechanical stop located under the broom assembly. Thus, when the operator wants to change the vertical position of the broom bristles with respect to the surface of the road or runway, it is necessary for the operator to crawl under the broom assembly in the snow or debris and physically adjust the position of the mechanical stop.
The brooms typically found on the front of a truck include a plurality of bristle assemblies which engage a rotating broom core. These bristle assemblies are mounted on a core assembly which is driven by a variety of different drive systems. The broom bristles are made of steel wire which gradually wear down from use. The contact area or xe2x80x9cpatternxe2x80x9d formed by the end of the bristles and the runway surface should be between 2xe2x80x3-6xe2x80x3 wide depending upon snow conditions for effective snow or debris removal. As the bristles wear down, the pattern width decreases. Accordingly, the broom must be repositioned vertically to maintain the desired pattern width.
The brooms typically have an operational life of about 60 hours, at which time the bristles are effectively worn down to their mountings. Thus, there is an ongoing requirement for height adjustment of the broom assembly as the broom bristles wear or become shorter. The relatively inaccessible location under the broom of the mechanical system for adjusting the sweep pattern makes the ongoing vertical repositioning problematic. What is needed is a mechanism for controlling the height adjustment of the broom assembly which is sensitive to changes in the position of the broom and easily accessible to the operator.
The present invention is an apparatus and method for utilization of a proximity sensor to control the height adjustment of vehicle-mounted devices for use in clearing snow or debris from a road or runway. To make the adjustment of the vertical height of the broom more convenient, the control mechanism which senses and controls the height of the broom has been moved from underneath the broom to the top of the broom.
A shaft and proximity sensor are located on the top of the broom assembly to indicate the vertical position of the broom. One end of the shaft is mounted on the broom, while the other end is attached to a ratchet assembly. A threadable collar is located on the central portion of the shaft. The rod and collar move past the proximity sensor when the broom height changes.
The proximity sensor produces and monitors a magnetic field. When the collar moves past the proximity sensor, it distorts the magnetic field and causes the proximity sensor to stop the electrical signal to the valve controlling the height of the broom. The broom height control mechanism is adjusted by the ratchet assembly which tightens a nut on the end of the threaded portion of the shaft which changes the position of the collar on the shaft.